The superior colliculus: New insights into an evolutionarily ancient structure.

The superior colliculus is a structure located in the dorsal midbrain with well conserved function and connectivity across species. Essential for survival, the superior colliculus has evolved to trigger rapid orientation and avoidance movements in response to external stimuli. The increasing recognition of the widespread connectivity of the superior colliculus, not only with brainstem and spinal cord, but also with virtually all brain structures, has rekindled the interest on this structure and revealed novel roles in the past few years. In this review, we focus on the most recent advancements in understanding its cellular composition, connectivity and function, with a particular focus on how the cellular diversity and connectivity arises during development, as well as on its recent role in the emergence of sensory circuits.